Process for producing aerated soap



April 23, 1946. J, w. BODMAN PROCESS FOR PRODUCING AERATED SOAP Filed Sept. 23, 1940 2 Sheets-Sheet l m n M flea/7K ATTORNEYS April 23, 1946. J. w. BODMAN v PROCESS FOR PRODUCING AERATED SOAP 2 Sheets-Sheet 2 Filed Sept. 23, 1940 Patented Apr. 23, 1946 UNITED STATE John W. Bodman, Winchester, Mass., assignor to Lever Brothers Company, Cambridge, Mass., a corporation of Maine Application September 23, 1940, Serial No, 358,006 2 Claims. (Cl. 252-134) This invention relates to the production of aerated detergent masses suitable for laundry and toilet uses.

Detergent, masses such as soap, aerated sufiiciently to float have long been in demand comas as desired.

In the drawings, Fig. 1 is a vertical section of a conventional type of Banbury mixer. The right hand rotor is shown in Fig. 2 by a section taken in the direction of the arrow marked A along the line 6--6 of Fig. 1. Fig. 3 is a side elevation of the same rotor, the view being taken in. the direction of the arrow marked B in Fig. 1.

In the drawings, Fig, 4 is another type of apparatus suitable for producing my desired mercially. Such aerated soaps have commonly 5 product. been produced in a crutcher by agitating the soap The apparatus illustrated in the drawings, Fig. while in a viscous or molten condition so as to 1, Fig. 2 and Fig, 3, comprises two parallellyentrap and disseminate air throughout the mass. arranged chambers 4 and 5 communicating at Examination of aerated soaps made by the prior their inner sides which open into a central chamart processes discloses that the air bubbles are her 5. These three inter-communicating chamof all sizes and predominantly coarse and fur- .bers together constitute a treating chamber in ther are unevenly distributed throughout the soap which the soap stock is subjected to heat, presbar or cake. sure and a thorough mixing or working over. The By the practice of my invention it is possible chambers 4 and 5 are respectively formed by the to produce a soap, in cake or bar form, having a cylindrical walls, indicated at 1 and 8, the upper characterizin dispersion of uniform cellsor inner ends of which terminate in the vertical bubbles of a compatible gas or vapor throughout walls 9 and II! which form a mouth 14 through the mass, the cells or bubbles having a fineness which the soap stock is fed into the chambers and and auniformity or evenness of distribution never which is adapted to be closed by a plunger ll. heretofore obtained. The means for working over or thoroughly mix- The aerated product of my invention, particug, shearing and eading the soap stock comlarly in a floating form, has a unique but characprises the rotors I2 mounted axially in the chamteristic color and appearance, making it highly bers 4 and 5. Each of the two rotors is provided desirable as compared with the prior aerated with two interrupted spiral blades l3. The desoaps ilabl tails of the shape and arrangement of the spiral My product may be made from any usual launblades l3 and their mode of operation are set dry or toilet soap stocks. It is important, in genforth in the patent to Banbury O- 0 7 eral, that the starting stock be capable of condated October 3, 1916. version to ,a continuous workable state, permitv3o In order thatthe temperature of the soap mass ting the incorporation of air or other compatible in the treating chamber may be regulated, the gas or vapor with the mass. This may be done walls 1 and "8 are jacketed, being provided with by the control of heating or moisture conditions, the shell or casing sections l5 and I6 which are for example. Whether such a state is molten, separated irom the walls by the ribs I1. Steam semi-fluid, fluid, plastic or otherwise is immateor other heating medium may be introduced into rial so long as air, for example, can be dispersed the spaces l8 defined by the walls and the casing and so retained until solidification of the mass. sections. 1

In the accompanying drawings I have illus- The pressure under which the soap mass is trated two forms of apparatus suitable for pracworked may be supplied by the weight of the ticing my invention' The details of the apparatus 40 Plunger l l which serves to close the mouth It may be modified and other apparatus substituted, when the rotors l2 arekneading and working the. I however, without departing from the invention? so soap mass in the treating chamber. If the weight long as the desired unique effects are'reproduced. of the plunger is not sufficient to exert the re- In general, it is preferred that the apparatus quired preS n t e s p mass, additional presbe jacketed or otherwise adapted to a temperasure may be supplied by steam or compressed air ture control during the process; enclosed to peracting on the upper side of a piston 20 mounted mit the application of pressures suitable for the on the upper end of a rod 2| secured at its lower mass under treatment; and provided with a end to the plun er II. The piston 20 slides in means capable of working the mass to facilitate a vertical cylinder 22 suppor ed on the upper end the incorporation in the mass of the compatible of a hopper 23 in turn supported on the upper ends of the walls 9 and. Ill. The top end of the cylinder 22 is closed by a cover 24 and the lower end of the cylinder is provided 'with a gland box 25 in which are located the glands 26 to prevent leakage of fluid around the piston rod 2|.

The duct 21 at the upper end of the cylinder 22 admit steam or compressed air to the upper side of the piston to hold the plunger I I down in the mouth I4 during the working of the soap mass; and the duct 28 admits steam or compressed air to the lower side of the piston to lift theplunger out of the mouth I4 on the completion of the soap treating operation. Even when no pressure is exerted on the plunger through the piston, the plunger is conveniently lifted by means of the piston.

treating chamber through the mouth l4, the upper end of the latter registers with the opening 29 in the lower end of the hopper 23, the front side of which has a swinging door 30.

The treated material is discharged from the treating chamber through an opening formed in the central lower portions of the walls I and 8.

This opening is closed by the curved wall sections 3| and 32 which form the inner lowerends of the walls I and 8 and which meet in a curved apex at this point. The wall sections 3| and 32 with the casing section 33 define a space which forms part of the jacket of the cylindrical chambers 4 and 5. The parts 3|, 32 and 33 constitute a gate which serves to control the discharge opening of the treating chamber. For this purpose the gate is connected with an arm 35 pivoted at 36. Projecting forwardly from the arm is a counterweight 31. The gate is held in closed position by a pivoted arm 38. When the contents of the treating chamber are to be discharged, the

arm 38 is swung to the right, which releases the gate and permits it to swing on its pivot 36.

The practice of the process of producing the the point where the soap contacts with the inner surfaces of the walls I and 8 this wedging action becomes a shearing action. As the blades move against the soap mass the latter i not only sub- Jected, the wedging and shearing action against the er surfaces of the walls I and B but is also pushed axially of the blades toward the inner ends thereof which overlap somewhat, asindicated best in Fig. 3, with the result that all parts I of the soap mass are constantly changing their positions and are overlapped and kneaded together. Hence all parts of the soap mass are presented to the interior surfaces of the walls 1 and 8 to receive the heat therefrom, and also whatever air is present in the soap mass is equally and uniformly distributed throughout the soap mass in microscopic cells or bubbles, by the constant and continued shifting of all portions of the soap mass.

The pressure under which the plasticized or partially melted soap mass is thus thoroughly worked and agitated apparently facilitates the process. After the working of the stock has been carried out for 15 or 20 minutes in the apparatus described the soap stock is released and the product cooled. The releasing preferably should take place into some form-imparting means, from which the solidified mass can be removed and cut up into cakes or bars.

Although these steps of releasing and cooling I can be carried out in any preferred manner, I

novel soap may beginat any point in the history of the soap stock after saponification. The process may be applied equally well to settled kettle soap, or to soap made by the semi-boiling and cold-boiling, processes. I set forth below for the purposes of illustration a description of the operation of the process as applied to the treatment of neat kettle soap. About 150 pounds of soap chips are introduced into the apparatus through the hopper 23 and the plunger or weight II is lowered into the mouth I4 leading into the treatsure exerted on-the piston 20 will exert a pressure of about twenty-five pounds per square inch .lng chamber constituted by the chambers 4, 5 and -6. The weight-0f the plunger II plus the pres on the soap mass in the treating chamber, it being understood that various pressures may be employed depending on the character of the soap product desired. The steam or other heating medium circulating in the jacket of the treating chamberwill heat the soap mass preferably to a temperature of from about 160 to about 225 F., thereby plasticizing it. The rotors I2 turn relatively slowly and preferably at different speeds, the left hand rotor, viewing Fig. 1, turning at about 34.2 revolutions per minute and the right hand rotor turning at about 13 revolutions per minute. Usuallly, no extra supply of air is introduced into the treating chamber beyond that which enters with the soap and that which is contained or dissolved in the soap from its previone treatment, this amount of air being usually suflicient .when uniformly distributed throughout the soap mass in minute cells or bubbles to produce a floating soap. However, if desired, additional air may be added.

The rotating spiral blades I3 in conjunction with the interior surfaces of the walls I and 8 exert a wedgingaction on the soap mass, and at shall disclose a specific operation in connection with my process 'For example, on the completion of the process the rotors may be shut down and the pressure on the soap mass in the treating chamber relieved, either by lifting the plunger I I or by opening the gate. I prefer, however, to release the pressure on the chamber before opening the gate in this particular operation. The

treated soap mass is discharged by throwing the arm 38 to the right and then moving the counterweight 31 upwardly, which causes the gate to swing downwardly, discharging the soap into a container. Due to the difierential in temperature between that at which the operation is carried out, and room temperature, there is an immediate cooling of the discharged soap mass. If desired, there may be a preliminary cooling by passing a cooling medium through 'the jacket surrounding the mixer. The solidified soap mass may then be cut up into cakes and bars in much the same manner as framed or milled soap is cut up into cakes and bars. The cutting of the soap mass into cakes and bars and the pressing of the cakes and bars into the ultimate finished product does not substantially affect the specific gravity of the soap and thus the floating characteristics.

Instead of carrying out my process as a batch operation, as hereinbefore described, I may continuously practice my process. For example, in the type of apparatus described above, the soap stock, either fluid or solid, may be introduced ess continuously.

Fig. 4 discloses another suitable apparatus. Thisapparatus comprises a cylindrical soap chamber I 0| having a heating jacket I02 con- The cooling can take place within the form-imparting means.

angle ,of approximately 12 from the perpendicular to the face of the piston so that the soap is prevented from retracing its path exactly through the piston. The piston I03 may be replaced, if desired, by another having diiferent or more suitable perforations for working a given composition.

The temperature of a soap mass in the soap chamber ill-i may be measured by means of a thermocouple I05, the junction of which is carried by a thin walled metal tip I01 extending into the soap and thermally and electrically insulated from the piston M3 by suitable meansof the chamber through which the piston rod I04 extends, is closed by means of a closely fitting cylindrical plunger I09 which is adapted to move longitudinally of the soap chamber as required to compensate for the change in available space as the piston rod I goes in and out. Excessive movement of the plunger 409 is prevented by check plate I I0 and coil springs III. V

The opposite end of the chamber is closed by means of a valve plug 11 I2 provided with means for measuring the pressure exerted upon the soap by the forward stroke of the piston I03. The plug H2 is formed with an oil space II3 separated from the soap by means of a flexible diaphragm II4 fitted to the face of the plug whereby the pressure on the oil may be considered equal to the pressure on the soap. As a result, the soap pressures may be read by means of a suitable pressure gauge I I5 connected to the oil space II3 by means of a tubular supporting shaft I I6.

When the treatment of the soap has been completed, the sliding gate I I! to a water cooled mold H8 is opened and ,valve plug H2 is' moved so as to permit passage of the soapfrom the chamber into the mold. The soap may be extruded from the chamber in any convenient manner such as by coupling the piston I03 with the plunger I09 after removing the check plate H0 and pressure plate H9. The mold lI8-is preferably fitted with a weighted plunger I20 which rises as the soap is extruded into the mold while maintaining some slight pressure downward on the soap. The extent to which the plunger I20 can rise in the mold is determined by a stop I2 I ,which is used in order to predetermine the size of the bar and to hold the same under a positive pressure during the initial period of cooling. When the extruded soap has been cooled, the mold is detached and the solidified bar removed.

If the chamber IOI of the apparatus of Fig. 4 is charged with the soap to be treated or tested,

is heated by means of hot Water circulating in the jacket and the perforated piston is reciprocated, the consistency of the soap mass is found to change as the temperature rises. These changes are observed by the pressure developed on the forward stroke of the piston through the soap mass.

1 have successfully utilized this apparatus with the piston I03 reciprocating at 8.6 strokes per minute.

As an example of my process utilizing the piston-treating apparatus of Fig. 4, the apparatus is charged with soap chips made from a kettle soap of an tallow and 20% cocoanut oil formula. These chips contain approximately 30% water. They are thoroughly worked in the apparatus for about 15 minutes at a static pressure of about 20 pounds gauge, and at a temperature of 160 F. The mass is then released to a mold and cooled. The resulting soap bar upon examination is found to have a specific gravity of about 0.71 and a whiteness and opacity so superior to that of known aerated soaps as to be unique. microscopic examination showed that the air bubbles were unusually minute and uniform in size and, furthermore, that they appeared to be uniformly distributed throughout the mass, characteristics not found in any other aerated soaps.

As another exr mple, I charge the piston apparatus with a similar soap stock in chip form and thoroughly work the mass for 20 minutes, at

a temperature of F. and under a static pres-' sure of about 20 pounds gauge to aerate it. The specific gravity of the bar produced is 0.83 and is found also to have a unique air distribution, giving it the characterizing whiteness and opac ity.

I have also aerated a similar soap stock in my piston apparatus utilizing temperatures of 140 F. and a static pressure of about 60 pounds gauge. Under these conditions the specific gravity of the soap bar was found to be 0.82 and it had acquired the characterizing microscopic air cells and uniformity of distribution typical of the product produced by my process.

As a result of the present disclosure, other apparatus for practicing the invention, as well as this reason, the apparatus described, as well as the processes in which they are used, are for the purpose of illustration only and should not be considered as imposing limitations on the broader aspects of my invention.

In treating a soap stock in a solid chipped form according to the process of the present invention, sufficient air usually enters the mixing zone with the charge to impart floating properties to the final soap product. However, 'if the soap stock charged is.of such a nature as to not include suflicient air to impart the desired aerated properties on subsequent processing, additional air may be introduced into the mass tobe treated prior to or during the processing. The specific gravity of the product may be controlled over a wide range bysuitably adjusting the temperature sired proportion of air, for example, in "the final product. A degree of. aeration such that the volume of the air cells or bubbles will equal 35% or more of the volume of the soap product may be obtained. A floating soap or other detergent mass produced by the present invention may have a specific gravity of from about 0.50 to about 0.98.

Satisfactory soaps may beproduced at temperatures ranging from about 140 F. to about 225 F. with a soap stock of the illustrative type used by way of example. The foregoing temperatures, of course, would be modified depending upon the detergent component used, the moisture content, and the presence of other ingredients, the important factor being that the mass during processing should be in a workable state' somewhat similar, at least, to the molten or semi-fluid to fluid state of ordinary soap stocks at temperatures of 160 F. to 180 F., for example.

The temperature to produce a desired viscosity in soap is, in general, inversely proportional to the moisture content. As a rule, I am able to aerate within a somewhat lower range of temperatures than has heretofore been possible. This may be because of the intense working under pressure which is a major feature of my process. The lower limit of temperature which may be used for the pressure aeration of soap will depend in part on the eifectiveness of the apparatus used in accomplishing the working action described, and in part on other factors, such as the tendency of the dispersed gas bubbles or cells upon release to move within the mass and to coalesce into larger bubbles or voids and the manner in which the mass under treatment will coalesce to form a coherent aerated bar after working at the lower temperatures.

I appreciate, of course, that the type or condition of the charging stock may have an important bearing on the commercial aspects of the process. It will be understood, however, that the state or condition of the charging stock in the practice of my process is not important from the standpoint of my invention in that, for example, it may be fluid, molten, or solid, continuous or comminuted. The important factor is the condition of the mass during treatment as described herein.

The super-imposed or static pressure to which the soap mass is subjected will preferably be correlated to the temperature, the pressure usually being increased with a rise in temperature and ranging from slightly over atmospheric pressure to 100. pounds per square inch and over. Satisfactory results, however, have been obtained by maintaining a given pressure on the soap mass,.

say about 25 pounds per square inch, and varying the temperature according to the characterizing properties desired in the new soap. It is desirable to subject the soap mass to pressure to secure an increased working action and also to prevent escape of moisture and air from the mass. It is also desirable while the soap stock is being subjected to both heat and pressure to agitate it thoroughly by mechanical means so as to uniformly distribute any entrapped, occluded, as well as dissolved air and gases throughout the massunder treatment. This agitation is advantageously carried on in such a manner that not only are all portions of .the soap mass exposed equally to the source of heat, but also all portions of the soap mass are moved relatively to each other.

I do not wish to be limited to any particular theory of operation of my process. However, it will be noted that in each of the apparatus described above as suitable for practicing my 'proc- 'ess, there is the common feature of intensely intimately dispersed throughout the mass undertreatment. With each following reduction or removal of pressure the gas may actually be drawn out of solution. Such released gas would be in a highly dispersed condition, and with a suitablev adjustment of the working conditions, the imposed pressure and th viscosity of the mass as controlled by temperature, for example, so as to minimize upon release the recombining of the dispersed gas cells, it is understandable how a final product may be obtained in which the dispersion approaches colloidal proportions.

I have noted that if very low static pressures are utilized in my process, it is desirable to have such a, working action during the processing as would tend to produce the greatest number and maximum amount of these internal positive and negative pressures on the treated mass. However,

the use of material static pressures is found dcsirable in any event for increasing the working action.

In floating soaps, as heretofore produced, the entrapped air bubbles vary considerably in size but, in general, are relatively large'and are irregularly distributed throughout the body of the soap. In the aerated or floating soap, for ex- .ample, capable of being produced by the practice of the present process, on the contrary the air bubbles entrapped in the solidified mass are characteristically of a minute and uniform size and are uniformly distributed throughout the body of the soap. As a result of my process, the bubbles or cells are so small and are so evenly distributed throughout the body of the detergent mass that when the resulting solidified mass is cut up into cakes or bars, the presence of the bubbles or cells is not noticeable to the unaided eye and a uniqueprocess, indicates that a predominant proportion of the bubbles may have resulted from the en- .trapping upon solidification of air bubbles substantially as released from solution in a colloidally dispersed form. I have found that the bubbles may be of the order of from 20 to thousandths of a. millimeter. (.0008 inch to .00024 inch) in diameter.

'I'he presentapplication is a continuation, in

part, of my application filed June 18, 1936, Serial No. 85,985, which in turn is a continuation of my application filed April 8, 1933, Serial N0. 665,063.

My application Serial No. 85,985 has issued as Patent No. 2,215,539; dated September 24, 1940.

I claim: 1. A process for producing an aerated, floating soap mass suitable for use in bar or cake form,

having a compatibl gas uniformly dispersed throughout the mass in the form of microscopic cells or bubbles and suitable for producing a unique whiteness and opaqueness in an uncolored.

soap mass, comprising Working a continuous soap mass in a pressure chamber while under pressure and in the presence of a compatible gas, uni

' formly distributing a material proportion of aid and in the presence 01' a compatible gas, uniiormly distributing a mlterial proportion of said ga throughout the soap mass in the form of microscopic cells" or bubbles, forcing said soap mass from said pressure chamber into a forming means while maintaining pressure thereon and maintaining said soap mass under pressure in saidtorming means while further cooling said mass. JOHN w. BobMAN. 

